Pairing correlations of cold fermionic gases at overflow from a narrow to a wide harmonic trap

Within the context of Hartree-Fock-Bogoliubov theory, we study the behavior of superfluid Fermi systems when they pass from a small to a large container. Such systems can be now realized thanks to recent progress in experimental techniques. It will allow to better understand pairing properties at overflow and in general in rapidly varying external potentials

Excitation energy dependence of symmetry energy of finite nuclei

A finite range density and momentum dependent effective interaction is used to calculate the density and temperature dependence of the symmetry energy coefficient Csym(rho,T) of infinite nuclear matter. This symmetry energy is then used in the local density approximation to evaluate the excitation energy dependence of the symmetry energy coefficient of finite nuclei in a microcanonical formulation that accounts for thermal and expansion effects. The results are in good harmony with the recently reported experimental data from energetic nucleus-nucleus collisions.Comment: 11 pages, 3 figures, revtex4; minor changes in text, axis label in figure 1 correcte

Density reorganization in hot nuclei

The density profile of a hot nuclear system produced in intermediate energy heavy ion collisions is studied in a microcanonical formulation with a momentum and density dependent finite range interaction. The caloric curve and the density evolution with excitation are calculated for a number of systems for the equilibrium mononuclear configuration; they compare favorably with the recent experimental data. The studied density fluctuations are seen to build up rapidly beyond an excitation energy of 8 MeV/u indicating the instability of the system towards nuclear disassembly. Explicit introduction of deformation in the expansion path of the heated nucleus, however, shows that the system might fragment even earlier. We also explore the effects of the nuclear equation of state and of the mass and isospin asymmetry on the nuclear equilibrium configuration and the relevant experimental observables.Comment: 20 pages, 12 figures, revtex

Symmetry energy of warm nuclear systems

The temperature dependence of the symmetry energy and symmetry free energy coefficients of infinite nuclear matter and of finite nuclei is investigated. For infinite matter, both these coefficients are found to have a weaker dependence on temperature at densities close to saturation; at low but homogeneous densities, the temperature dependence becomes stronger. For finite systems, different definitions of symmetry energy coefficients are encountered in the literature yielding different values. A resolution to this problem is suggested from a global liquid-drop-inspired fit of the energies and free energies of a host of nuclei covering the entire periodic table. The hot nucleus is modeled in a subtracted finite-temperature-Thomas-Fermi framework, with dynamical surface phonon coupling to nucleonic motion plugged in. Contrary to infinite nuclear matter, a substantial change in the symmetry energy coefficients is observed for finite nuclei with temperature.Comment: 12 pages, including 11 figures, appearing in special issue of EPJ-A on Nuclear Symmetry Energ

Light projectile elastic scattering by nuclei described by the Gogny interaction

In this work, we study the elastic scattering of some light particles, such as $^2$H, $^3$H, $^3$He, and $^4$He, by heavy target nuclei with an extended Watanabe model, which uses as input the neutron-nucleus and proton-nucleus optical potentials and the ground-state wave functions of the projectile. The nucleon-nucleus optical potential used in this work was obtained within a semi-microscopic nuclear matter approach, whose real and imaginary parts are provided by the first and second-order terms, respectively, of the Taylor expansion of the Brueckner-Hartree-Fock mass operator obtained with the reaction G-matrix built up with the Gogny force \cite{lopez21}. The angular distributions of the scattering of $^2$H, $^3$H, $^3$He, and $^4$He from different target nuclei and at a different incident energy of the projectile computed with this model are analyzed. The reaction cross-sections corresponding to some of these scattering processes are also calculated. Our results are compared with the experimental values as well as with another Watanabe calculation where the nucleon-nucleus the optical potential is provided by the phenomenological K\"oning-Delaroche model. The limitations of the extended Watanabe model used in this work are also discussed

The effects of medium on nuclear properties in multifragmentation

In multifragmentation of hot nuclear matter, properties of fragments embedded in a soup of nucleonic gas and other fragments should be modified as compared with isolated nuclei. Such modifications are studied within a simple model where only nucleons and one kind of heavy nuclei are considered. The interaction between different species is described with a momentum-dependent two-body potential whose parameters are fitted to reproduce properties of cold isolated nuclei. The internal energy of heavy fragments is parametrized according to a liquid-drop model with density and temperature dependent parameters. Calculations are carried out for several subnuclear densities and moderate temperatures, for isospin-symmetric and asymmetric systems. We find that the fragments get stretched due to interactions with the medium and their binding energies decrease with increasing temperature and density of nuclear matter.Comment: 12 pages, 11 figures, Phys. Rev.C (in press